Project Summary/Abstract Sedentariness can lead to excess risk for maternal and child mortality and morbidity. Most pregnant women, however, become sedentary in the 3rd trimester. In our randomized controlled trial with a high-risk group of sedentary overweight/obese pregnant women with a history of preeclampsia, we found that 10 or more weeks of stretching exercise (SE) reduced the incidence of preeclampsia - a significant risk factor for cardiovascular disease - by lowering blood pressure (BP) and enhancing antioxidant up-regulation and production, compared to walking, to which pregnant women adhered poorly. We plan to test if this effect can be extended to broader populations of pregnant women. From our pilot study of healthy pregnant women, of which 84% were overweight/obese, we reported promising results of the short-term effects of SEs on BP and sympatho-vagal balance. Thus, we propose to test the effects of a novel SE intervention on cardiovascular health in obese pregnant women in the 3rd trimester. We include evidence-based behavioral strategies to enhance adherence. A session of SE includes 30 minutes of sequential static stretching of large skeletal muscle groups for 20 seconds, 3 times per muscle group. Although little is known about cardiovascular effects of SE, our preliminary findings were unexpected yet consistent across our studies. If the findings persist, SE would be an effective, accessible, cost-efficient way for obese pregnant women to promote their health and reduce risk of cardiovascular complications of pregnancy. The study of SE interventions is therefore justified. In this 2-arm RCT we will determine if a SE is superior to a control condition of enhanced usual care (eUC) which includes moderate/vigorous activity, specifically walking, for 30 minutes 5 days/week as recommended by the American College of Obstetricians and Gynecologists. Both the treatment and control arms will receive a supportive behavioral intervention to facilitate adherence. Primary outcomes are BP, sympatho-vagal balance, and arterial stiffness assessed at baseline (27 weeks? gestation), then at 5 and 10 weeks later, and at 32 and 37 weeks? gestation. We will compare SE to eUC (n = 306; 153 per arm) and examine selected cardiovascular functions by which SE may be effective. The Aims are: Aim 1: To test the efficacy of SE intervention on improving cardiovascular health compared to eUC with respect to selected indicators of cardiovascular function (BP, sympatho-vagal balance and arterial stiffness), controlling for anxiety, age, race/ethnicity, BMI, and smoking; Aim 2: To test the efficacy of the SE intervention on maternal, fetal, and neonatal composite outcomes compared to eUC. Aim 3: To explore the relationship between adherence and cardiovascular measures and pregnancy complications. Our goals fit NINR?s strategic goal of promoting health and preventing illness across health conditions, settings, the lifespan, and in minority and underserved populations, who bear higher burden of obesity. Stretching exercise may be viable for preventing cardiovascular illness and is known to have high acceptance, better adherence, no known untoward side effects, and promising preliminary evidence of effectiveness.